Gen'ei no Magen Shinigami
by Lord Lucifer The 8th
Summary: Aizen is summoned into the world of DxD! Watch his misadventures with the DxD cast and how he developed his love life, while at the same time throwing canon to the curb! Good Aizen! Op Aizen! Aizen x Harem!


Author's Note: Hey guys my name is Lord Lucifer The 8th, and welcome to my story! I'm new here so please be easy, however critique and constructive criticism is welcome as I like to learn from my mistakes! Although if it can be helped please keep the flames to a minimum as that's just bullying and story bashing. Without further adieu let's get into the story!

Tags: Mass harem, Godlike, OP,

Pairing: Harem

"Talking"- People

 _"Thinking"_ \- People

"Technique"

 _*Sounds*_

 **"Talking"** \- Beast, Soul, Sacred Gear, Other

 _ **"Thinking"**_ \- Beast, Soul, Sacred Gear, Other

Unknown Location

 _*Splish*_

 _*Splash*_

The sounds of dripping water echoes around the void. Empty of everything even light. But in the center of the darkness sits a mass of contradiction. It's nothingness, and yet there's something…. An existence of any kind should logically be impossible in a place devoid of everything vital to any life. Regardless of these laws there is what looks to be a chair in the middle of everything, with the being occupying it indescribable due to the countless materials bounding him. A single glance at these bindings can show that they were made to hold back extreme power, but what does that have to do with him?

Afterall what would power matter in this void, a plane so similar in likeness to himself, a contradiction.

Mugen

 _"Curse these damn binds!"_ thought the object of interest, the man in the center of the void.

 _"I despise my uselessness in this world! To think I, Aizen Sosuke, would be forced to watch from the sidelines as a war I could easily end destroys the world around it, all because of these GODDAMN BINDS!"_ The man now known as Aizen Sosuke raged in his mind. He would've said it out loud if not for the seal covering his mouth. The man knew he had done some wrong but was this really necessary? Afterall if he wasn't in this chair he could've easily ended the war in their favor.

 _"Although I suppose I did kill the government, start my own war, and try to overthrow the Soul King. As well as numerous other atrocities."_ Aizen mused to himself, though in his defence he had his reasons. Good intentions beneath the mask of a monster, though the actions taken because of those intentions are less than stellar, he was trying to make the world right.

 _"In hindsight not my best plan, fighting for peace is like rolling around in mud to get clean"_ these thoughts often plagued his head, he had many regrets and most of them were directly related to his own actions. He wanted to make things right but it's too late now, everyone was already dead, so who was there to save? The Quincy King Yhwach had decimated the Shinigami and the Hollow forces… nothing was left but the Quincy and the few humans that survived the war. He regrets his inability to either end or prevent the war. He regrets the deaths he could have stopped. And finally…. He regrets the pain the world has been knew that should he have been free he could have decimated Yhwach's army and the Quincy King himself. And the only reason he was bound to this chair was because of his own mistakes. He had felt, and in a way seen Ichigo Kurosaki lead herself and the Shinigami/Hollow forces into battle, only to be beaten back and killed, it made the hole where his heart should be his actions all he desired was peace, and it hurt him to betray soul society, to kill his own friends, to act so callous and arrogant towards them. In spite of his attitude he never stopped caring for all of them, and beared a heavy pain and burden, all for his attempt at peace. He was a fool. He only wished he had a second chance to protect, to bring about peace. But why should he get any desire of his filled? He was lower than scum… in his eyes. No, he doesn't deserve anything other than pain, not even the sweet release of death. As he was getting ready to once again resign himself from his thoughts and endure the engulfing silence of the void like he had done for many years before, he heard a voice echo throughout the void.

"Hearken and heed my words my beautiful servant somewhere out there, rejoice! For you have been given new life in the name of the house of Gremory. Come Forth!"

Aizen saw black.

Underworld, Gremory Estate

"Do you really think this will work, Rias?" asked a buxom, dark violet haired beauty.

"It has to, Akeno, I don't have any other chance," responded Rias, a crimson haired, slightly less busty girl.

"But you know the summoning only has a point five percent chance of working, maybe we should start looking for a powerful peerage member elsewhere?"

"We've looked everywhere else, Akeno, this is the only option left, and we only get one chance, father will get upset if we have to waste Leviathan-sama's time more than we already have. I'm afraid that if this doesn't work we're doomed. Not even brother can help if this fails, and I refuse to marry that bastard Riser-teme!"

"I know, Rias, I don't want you to marry him either, he's a pig."

"Now now, Ria-tan, Akeno-tan, calm down, with my magical girl powers there's no chance you'll fail!"

"Our apologies, Leviathan-sama, you're right." The woman they were talking to was shorter than the both of them, although her breast seemed to be slightly bigger than Rias's are, but still smaller than Akeno's. She had raven black hair tied in twin tails, violet eyes, a pretty face, and was wearing a magical girl cosplay outfit.

"That's fine Ria-tan, and how many times have I told you to call me Sera-tan!" the woman said puffing out her cheeks and pouting.

"If you insist Serafall-sama,"

"Muuuu! S-E-R-A-tan, not Serafall sama!" the now identified Serafall grumbled.

"As one of the Maou referring to you as that would be highly disrespectful,"

"Who cares! This is an order from the Maou, call me more familiarly!"

"That's a heavy abuse of power,"

"Yeah, well-" Serafall got cut off as the summoning circle flared up and started emitting a red light.

"Well Ria-tan it looks like it's working, go ahead and put the pieces in,"

"Hai, Leviathan-sama," Rias started walking towards the circle with a chess board in hand. When she reached it she put a pawn piece with wings on the circle which quickly got sucked up. She placed another on the circle, which again got sucked up. She repeated the process with a shocked look on her face which was shared by all others in the room. She put her last pawn on the circle but it kept on glowing.

"N-no way! It took eight mutation pawns!? Each one of those was equal to a queen piece!" stated Serafall with an astounded look on her face.

"Leviathan-sama, help!" exclaimed Rias as the circle was still glowing which indicated it needs more power.

"R-right!" Serafall responded quickly going over to it trying to gauge how much more power was needed, before her jaw dropped. She shakily grabbed a queen piece with wings, a mutation piece before sitting it on the circle. There was a big flash of light, then the glow died down to reveal a figure.

"Ara ara, Rias, It looks like you lucked out, that's quite a powerful servant. He's quite the looker too," Akeno broke the silence with a blush and some drool, the other two inhabitants of the room having a similar reaction before breaking out of their stupor. The figure was a brown haired handsome man with a toned body, which was visible due to his slightly tight clothing, a white, nearly skin tight top with a zipper, that flowed down to his knees acting like a cloak, under which were matching pants(espada uniform). His face was devoid of baby fat with nice features and a narrow border. A single strand of chocolate brown hair hung between his eyes.

"S-sera-tan, how did this happen? How will it work? He can't be both of our servants,"

"HA! You called me Sera-tan!" exclaimed Serafall in a childlike manner, causing Akeno and Rias to facepalm.

Minutes Later

"Excuse me, ladies but I might have a solution to your dilemma.", a voice spoke out above the conversation. All heads turned to stare at the figure whom they presumed unconscious.

"You're awake? For how long?" questioned Serafall.

"The entire time."

"Wha-?!"

"Before further questions are asked allow me a moment for my own."

"Ok ask away." Rias responded hesitantly.

"Forgive me, I've misspoken, I've got more statements than questions."

"Regardless please begin."

"Very well, I believe I have gleaned much of the essential information from my tactical unconsciousness, like how you're devils and that you summoned me to reincarnate me into one, which you have. However I do not know about any of the other entities in this world which I feel would be useful knowledge on my part."

"Well there are the fallen angels, angels who have fallen from grace and led by the Grigori, the organization of the fallen, and the angels whom are led by god. For a very long time these two factions and the devils have been in a three sided war, which has only recently come to a shaky peace. During the war the original four Maou's, the devil leaders, were killed and so new ones were elected in their place. During this there was devil civil war on whether or not to restart the war, but the peaceful side eventually won out. Then the evil pieces were created to reincarnate so that we can increase our numbers. The members of a reincarnated group under a master are called a peerage. There are other beings as well, but at the moment they're inconsequential and you can study them in your own time. Is that all?"

"Possibly, are there any other important facts I should know about?"

"Glad you asked," began Rias,"The artifacts known as sacred gears."

"Before you begin may I make an inference?"

"A-alright?"

"Can I assume these sacred gears are powers given to a select few? And that it can only be given to humans?"

"H-how did you?!"

"It's logical. The tone you used implies that these 'sacred gears' are some sort of blessing, something important, and the most likely meaning of that is a type of rare power, given to a select few. Lastly, I assumed that they can only be given to humans because for one, I don't sense any special power inside of you, which with you being high class devils it would make the most sense for one of you to have them, secondly, why would blessings been given to devils? It doesn't make sense to give extra power to already powerful races, it is much more understandable to give it to the weakest race, humans, to balance it out."

"Wow! You're so smart! Rias-tan was lucky to summon you!" exclaimed Serafall excitedly.

"There is no such thing as luck, only situations combined with circumstance."

"And wise too!" Serafall could once again be heard from the background. For a while everyone in the room was silent. Not in an uncomfortable way, everyone was still awed by the intelligence he displayed. The tension in the room was nonexistent, simply a tone of admiration and comfort. All of this caused by the one chocolate eyed man, who seemed to exude these relaxing qualities constantly.

"I thank you, but I am only saying a few words, you mustn't make any assumptions about me just yet."

"Well anyways back to the topic, your earlier guess was correct, sacred gears are powers gifted to humans by the biblical god, and there are many different types with several uses, political, combat, and other. Some of these can even allow humans to stand alongside the strongest supernatural beings. These are called the Longinus. There are 13 of them."

"That is indeed useful knowledge, thank you for your assistance."

"We also believe that you have one of them. We sense great power in you."

"That'd be the case regardless if I have one of these sacred gears."

"Oh and why is that?"

"Well I'm not a human, I'm a shinigami, an incredibly powerful one at that."

"Why should I believe you?"

"What reason would I have to lie? In any case I'll give you proof if you wish."

"I would like that very much."

"Very well. Right now my power is beyond the comprehension of you, transcendent to the highest caliber. I will bring it to the point that you can sense it, however it will only be a fraction of my power. A very small one. I can allow you to sense my full power but you'd probably suffocate. Is this agreeable?" The other occupants of the room looked at him in apprehension and doubt, before Rias sighs and nods her head.

"Fine I agree to your terms."

"Alright let's get started. Bakudo No. 103: Pawagado." A transparent rippling barrier surrounded the building that they were in which looked like an old school.

"This barrier will completely block any power signature no matter how good the sensor. Prepare yourselves, I will now release a fraction of my power." Everyone in the room tensed and waited in anticipation. All of the sudden a crushing force slammed down on the occupants of the room, everyone, including Serafall, fell to the floor. They were breathing heavily and the only reason they weren't unconscious was because Serafall guarded them with her power.

 _"Oh maou! This is twice as powerful as Ddraig! And this is only a small fraction of his power!?"_ thought Serafall, the other two having similar thoughts of disbelief and awe at his power. As soon as the pressure appeared, it was gone.

"Am I correct to believe that my previous display was sufficient proof?"

"Y-*cough*-yeah, i-it was." Rias replied shakily. As she recovered the man gained a contemplative face before a glow could be seen on his stomach. All the chess pieces previously inside him popped out.

"!?" everyone stared in shock. Hastily recovering, Serafall was quick to stop his actions.

"Wait! Stop!" the man raised an eyebrow.

"Forgive me, are these important?"

"Yes! They're what we used to turn you into a partial devil! They're also what makes you a member of our peerages!"

"Mm, indeed." the pieces sunk back into his body.

"Phew."

"Well now that we've established that I can easily undo your work and undermine your efforts, thus reverting me from being your peerage member/servant, allow us to have a discussion about my status and what will happen now." Everyone in the room looked at him tentatively.

"*Gulp*-Very well." Rias complied.

30 minutes later

Everyone sat around a large table preparing for a civil conversation.

"Alright let's get down to business."

"What would you like in exchange for remaining our peerage member?"

"I wish to bend the rules of the peerage."

"In what manner."

"Well since I can reject your pieces anyways, I would like to be different to a servant. I want to be treated as a friend or companion. I don't want your words to be law, closer to suggestions that I can reject. I've always had trouble with authority."

"Is that all you want?", a nod answered Serafall's question. She smile as Rias, the unknown man, and herself shook hands, finalizing the agreement.

"Then welcome to our peerages Stranger-chan!"

"My name is Sosuke, Aizen, call me as you wish."

"Ok Aizen-chan!"

"Sure Aizen-san"

"Now onto other pressing matters. Earlier I heard discussion of there being some problem with my being a part of both your peerages? Why do?" Rias, quick to answer, began explaining.

"It has never happened before so we are not sure what to do. Should you be treated as a Maou's peerage member or as the sister of a Maou's peerage member. Who will you represent or take orders/suggestions from? Things like that."

"That's a simple matter. I will act as both. I will represent both of you in social standing and I will take requests from the both of you. If they contradict I shall consider Serafall's more heavily due to her having more authority over a peerage than its king regardless because of her being a Maou. However since they aren't orders both are still options and depend on the situation but at base Serafall's will have more weight."

"That's…. a good idea." Serafall said thoughtfully at first, then with glee.

"I agree."

"Then it's settled! From this day forward the terms are set and I am a member of your peerages."

"Now back to the possibility of you having a sacred gear."

"Ah yes I have been feeling a foreign power in my body, that is most likely what you are talking about."

"Yay! Can you bring it out!?" Asked Serafall.

"Of course." Aizen stated matter of factly. A look of slight concentration appeared on his face before everyone felt a power spike and a glow illuminated the room. As their vision returned everyone looked towards his raised arm. Looks of awe appeared on some while others had looks of confusion.

"What is that?", asked a curvy girl with a pony tail.

"That, Akeno, would be the boosted gear! One of the thirteen Longinus!"

"Really? What does it do?"

"It doubles the user's power every ten seconds! To think on top of your own power you also have this!?"

"Indeed, what would you have me do now?", Aizen asked.

"Tell me, have you ever been to school?"

—

Hey guys it's me! Now for this and my other story expect very very slow updates as I'm not good at putting out quickly. If you haven't please go check out my Tokyo Ghoul story, it's gonna be pretty good. Well that's all see you later!


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